The present invention relates to a system for variable absorption of energy from automobile vehicle steering columns acting directly on, and in the direction of the axis of, the steering column and employing pyrotechnic charges. The system according to the invention applies in particular to a steering column whose depth or inclination can be adjusted or to a steering column whose depth and inclination can be adjusted. The invention can equally be applied to a steering column that is not adjustable.
Ongoing improvement in steering column safety requires manufacturers to master all the parameters of energy-absorbing systems. Accordingly, with regard to the method of absorbing energy by unwinding a wire, which is increasingly used on steering columns, consideration is being given to modulating the absorption of energy in accordance with characteristics such as, in particular, the weight of the driver, whether the driver""s seat-belt is fastened or not, the driver""s position relative to the steering wheel, and the speed of the vehicle, which characteristics all affect the steering wheel in the event of an impact.
The object of the present invention is to propose a variable energy-absorbing system that acts directly on, and in the direction of the axis of, the steering column, uses wires with a simple shape that is easy to make, enables quantified absorption of all or part of the energy required to be dissipated, takes into account characteristics of the driver and the vehicle, and is easy to install within the overall size of existing steering columns.
One embodiment of the invention relates to a system for variable absorption of energy from an automobile vehicle steering column which includes a steering shaft rotatably mounted in a body-tube to rotate about a steering axis. The body-tube is connected to a support system that is fixed to the chassis of the vehicle.
A fixed support member is fastened to the chassis of the vehicle and a mobile support member is connected to the fixed support member to constitute the support system. The mobile support member is connected to the fixed support member and immobilized thereon up to a particular value so that said immobilization ceases in the event of an impact.
Two coils are made from a metallic member with a particular section. The two coils are connected to the fixed support member and to the mobile support member. One of the two coils is disposed on one side of the vertical plane passing through the steering axis and the other coil is disposed on the other side of the vertical plane passing through the steering axis.
Each coil is connected to the fixed support member and to the mobile support member by connecting pins consisting of retaining rods.
Each coil is mounted on a roller that is disposed on a retaining pin constituting the connecting pin with one of the two support members. Each coil has a linear portion in substantially the same direction as the force to be damped and extended by a free end which is attached to a fastening pin constituting the connecting pin with the other support member.
One of the two connecting pins of each coil consists of a retaining rod that can be moved in the direction of its axis by a pyrotechnic displacement system actuated by an actuator system.
In the event of an impact, and depending on the value of the parameters adopted, the mobile support member is connected to the fixed support member by a required number of coils, which number can be determined in accordance with certain characteristics of the driver, the driver""s position relative to the steering wheel, whether the driver""s seat-belt is fastened or not, and in accordance with the speed of the vehicle. The mobile support member, which is connected to the body-tube, and therefore to the steering wheel, therefore moves relative to the fixed support member in the direction of the steering axis and absorbs some or all of the energy required to be dissipated.
The pyrotechnic displacement actuator system is arranged so that, in the event of an impact, the mobile support member is connected to the fixed support member by:
the two coils, or
one of the two coils, or
the other coil, or
no coil.
In another embodiment of the invention a single coil of a metallic member with a particular section is connected to the fixed support member and to the mobile support member. The coil is disposed on one side of the vertical plane passing through the steering axis. The pyrotechnic displacement actuator system is adapted so that, in the event of an impact, the mobile support member is connected to the fixed support member by:
the coil, or
no coil.
In some embodiments of the invention, the retaining pin of each of the coils is disposed in the fixed support member and the fastening pin of each of the two coils is disposed in the mobile support member.
In other embodiments of the invention, the retaining pin of each of the two coils is disposed in the mobile support member and the fastening pin of each of the two coils is disposed in the fixed support member.
In different possible structures of the invention, each coil has its two connecting pins which are substantially parallel to each other.
According a type of structure, the two connecting pins of each of the two coils are in a vertical plane. The two connecting pins are substantially parallel to each other and substantially perpendicular to the steering axis.
According another type of structure, the two connecting pins of each of the two coils are substantially horizontal and substantially perpendicular to the vertical plane passing through the steering axis.
In various other possible architectures in accordance with the invention, each coil has two connecting pins that are substantially perpendicular to each other.
According to a type of structure, the retaining pins of the two coils are each in a vertical plane. The retaining pins are substantially parallel to each other and substantially perpendicular to the steering axis. The fastening pins of the two coils are substantially horizontal and substantially perpendicular to the vertical plane passing through the steering axis.
According to another type of structure, the retaining pins of the two coils are substantially horizontal and substantially perpendicular to the vertical plane passing through the steering axis. The fastening pins of the two coils are each in a vertical plane. The fastening pins are substantially parallel to each other and substantially perpendicular to the steering axis.
In two types of detailed structure in accordance with the invention:
the fixed support member consists of two bases that are fastened to the chassis;
the mobile support member has two lateral portions and a connecting portion, each lateral portion is extended toward the outside by a mobile base including a housing in which the corresponding fixed base of the fixed support member is engaged, the mobile base is connected to the fixed base and immobilized therein up to a particular value so that the immobilization ceases in the event of an impact, and the housing of the mobile base and the fixed base are arranged to facilitate assembly and disengagement in the event of an impact;
a coil is disposed outside each lateral portion, each coil having its two connecting pins mutually perpendicular.
The first type of detailed structure consists in that
each retaining pin constitutes the connecting pin with the corresponding base and is in a vertical plane and is substantially perpendicular to the steering axis;
each fastening pin, which constitutes the connecting pin with the corresponding lateral portion, is substantially horizontal and substantially perpendicular to the vertical plane passing through the steering axis;
the fastening pin consists of a retaining rod that can be moved in the direction of its axis by the pyrotechnic displacement system;
the retaining pin of each of the two coils consists of a fixed retaining rod.
The second type of detailed structure consists in:
each retaining pin that constitutes the connecting pin with the corresponding lateral portion is substantially horizontal and substantially perpendicular to the vertical plane passing through the steering axis;
each connecting pin that constitutes the connecting pin with the corresponding fixed base is in a vertical plane and is substantially perpendicular to the steering axis;
the retaining pin consists of a retaining rod that can be moved in the direction of its axis by the pyrotechnic displacement system;
the fastening pin of each of the two coils consists of a fixed retaining rod.
In two other types of detailed structure in accordance with the invention:
the fixed support member consists of a base that is fastened to the chassis, the base being extended on each side by a substantially vertical lateral portion;
the mobile support member has two lateral portions and a connection portion, each mobile lateral portion includes a housing in which the corresponding fixed lateral portion of the fixed support member is engaged, the mobile lateral portion is connected to the fixed lateral portion and immobilized therein up to a particular value so that the immobilization ceases in the event of an impact, and the housing of the mobile lateral portion and the fixed lateral portion are arranged to facilitate assembly and disengagement in the event of an impact;
a coil is disposed outside each fixed lateral portion, each coil having its two connecting pins parallel to each other.
The first type of detailed structure consists in:
each retaining pin that constitutes the connecting pin with the corresponding fixed lateral portion is substantially horizontal and substantially perpendicular to the vertical plane passing through the steering axis;
each fastening pin that constitutes the connecting pin with the corresponding mobile lateral portion is substantially horizontal and is substantially perpendicular to the vertical plane passing through the steering axis;
the connecting pin consists of a retaining rod that can be moved in the direction of its axis by the pyrotechnic displacement system;
the retaining pin of each of the two coils consists of a fixed retaining rod.
The second type of detailed structure consists in that:
each fastening pin that constitutes the connecting pin with the corresponding fixed lateral portion is substantially horizontal and is substantially perpendicular to the vertical plane passing through the steering axis;
the retaining pin consists of a retaining rod that can be moved in the direction of its axis by the pyrotechnic displacement system;
the fastening pin of each of the two coils consists of a fixed retaining rod.
The variable energy-absorbing system in accordance with the invention therefore has the advantage of a structure that is simple to make, with guaranteed quality of fabrication when it is mass produced, as is the case in the automobile industry. Moreover, the system is easy to adapt to the overall size of existing steering columns. Finally, the variable energy-absorbing system matches the absorption of energy to the whole or a portion of that which is required, allowing in particular for the weight of the driver, the driver""s position relative to the steering wheel, the safety belt and the speed of the vehicle, whilst preserving the same unwinding travel.